Profile: The age of Hobsbawm: The people's historian is turning his long gaze to a short century, says Neal Ascherson

ERIC HOBSBAWM has written a new book and - typically - invented a new period to fit it. Age of Extremes is subtitled 'The Short Twentieth Century: 1914-1991'. This period fits neatly on to the nose of his 'Long Nineteenth Century', which lasted until 1914 and was the subject of his famous 'Three-Ages' trilogy. But this is more than a sequel. Hobsbawm, at 77, is stepping out of the ground which is history to him and writing about his own lifetime, about events and changes he remembers.

No historian now writing in English can match his overwhelming command of fact and source. But the key word is 'command'. Hobsbawm's capacity to store and retrieve detail has now reached a scale normally approached only by large archives with big staffs. Appropriately born in Alexandria, he is a walking Alexandrian Library of knowledge, above all concerned with the 19th century. At the same time, no symptoms of pedantry have appeared. Quite the contrary: as the years pass, Eric Hobsbawm's gift for startling, often seductive generalisations from his material has only grown. He is a historian, not a novelist, but the engine inside his narrow head is a Rolls-Royce imagination.

Back in the 1950s, nobody could have expected that he would become - by the 1990s - the best-known and most popular general historian of modern Europe. He was then a fellow of King's College, Cambridge, an embattled, slightly exotic figure. In the early period of the Cold War, his loyalty to the Communist Party marked him out. It was a time so paranoid that even the election of Noel Annan, a Labour supporter in those days, as Provost of King's moved one prominent Tory backbencher to come to Cambridge and play 'Rule Britannia]' fortissimo on the chapel organ in protest. Eric Hobsbawm's intellectual brilliance was already obvious enough, and well recognised by his academic contemporaries. But an invisible fence seemed to stand round his prospects. Britain's version of McCarthyism was weak and erratic, but Hobsbawm reckons he was lucky to get his first post as a history lecturer - at Birkbeck College, in London - before the Berlin crisis of 1948 put the Cold War into high gear. After that, as he has said, 'you didn't get promotion for 10 years, but nobody threw you out'. Annan, in his Our Age, recalls how political enemies kept Hobsbawm out of a Cambridge lectureship and for many years blocked his appointment to a professorial chair at Birkbeck even when he had 'seven major publications' to his credit.

BORN into a middle-class Jewish family in 1917, he was brought up in Vienna and Berlin until - after the death of his parents - he was sent to Britain to escape Hitler. It was in Berlin, as a 14-year-old, that he joined the Communist Party. Unlike so many of his friends and contemporaries, who quit over the Nazi-Soviet Pact or over Hungary in 1956, he never left it. This tenacity is not easy to explain. Once he said to me, with his ironic, lopsided grin, that 'one should never resign, but much better get expelled . . . what?' More explicitly, he told an interviewer recently that 'there are certain clubs of which I would not wish to be a member', meaning the ex-Communists. His loyalty, he suggested, was not to a party line but to something much more emotional: to 'the dream of general liberation' and to Communists he had known, many of them dead, who were 'models to follow in their unselfishness and devotion'. At the time of Hungary, he protested within the party, but more importantly decided that 'if I was going to do anything in the future, it was to try and re-jig myself as a sympathiser on the left, rather than as a militant'.

Deftly, he had turned his Communism from a prison into a free ticket for intellectual travel. This had enormous consequences. In Eastern Europe, he became famous as a 'revisionist' critic of Stalinism. In the West, it helped him to resist many temptations to commitment, like the student 'revolutions' of 1968, while at the same time providing the young with one book after another which gave their rebellious dreams new and imaginative pedigrees in history: Primitive Rebels (1959), which revealed levelling politics behind the activities of rural bandits, or Captain Swing (on the English agrarian revolt of 1830-31), which he wrote with George Rude in 1969. Earlier, with other Marxist historians, he had helped to start the journal Past and Present, which introduced to Britain the notion of 'people's history' - not just the story of working-class and popular struggle, but the continental idea that each class wrote its own history to satisfy its own requirements.

He also began to travel literally. The stuffy post-imperial provincialism of England had always provoked him, ever since he reached London as an adolescent, and in his room a visitor entered an alluring world in which the talk was of republican Spain, Vienna pre-Hitler, the state of the struggle in Algeria or southern Italy or Poland. Later he began to visit and study Latin America, and since his retirement from his chair at Birkbeck in 1982, he has spent much of his time in New York, teaching graduate students at the New School for Social Research. His home, the pretty, comfortable house in Hampstead where he and his wife Marlene have lived for many years now, remains a place where leftish British intellectuals encounter German scholars, Austrian sculptors, radical politicians and writers from South America.

Eric Hobsbawm has always hankered after the more generous world of continental Marxism, where large and confident Communist parties trained up generations of young people not only to take ideas seriously but to enjoy life with a radical gusto. Best of all, in the 1930s Popular Front times, there was a unity of the left which sank its differences in order to deal with the Fascist enemy. One way of understanding Hobsbawm's political activities in recent years is to say that he has been trying to recreate that world in Britain. His famous 1978 lecture, published as The Forward March of Labour Halted, warned that only a far wider social appeal could save any form of radical politics - let alone socialism. In the Thatcherite decade, he again scandalised the orthodox left by insisting that getting rid of the Tories justified even the compromise of a centre-left electoral alliance.

At 77, Eric Hobsbawm himself has changed little. The lean, gangling frame, the spectacles, the abundant grey hair, the tendency to open-necked shirts - all that is much as it was, and so is the curious, compelling voice: something of an old-fashioned Bloomsbury drawl, with a Mitteleuropa edge. But the world around Hobsbawm has changed suddenly and totally. This is the fascination of Age of Extremes. As a history of 'The Short Twentieth Century', it is also his obituary of the Bolshevik Revolution whose cause dominated most of his life.

Anyone who expected some act of contrition, some wringing of hands, does not know Eric Hobsbawm. Instead, he alters all the conventional proportions of his period. Its central event is no longer the capitalist / Communist rivalry, not even the rise and fall of totalitarian systems. It is what he calls 'The Golden Years': the period from the mid-1950s to about 1973 when the gigantic success of the capitalist 'mixed economy' (not the free market) changed the conditions of the human race more rapidly, completely and irrevocably than ever before, 'the most profound revolution in society since the Stone Age'. Compared to that, Communism and the Cold War were only 'of limited historical interest'. The Red Army saved Europe from Hitler, thereby saving capitalism, and the postwar Soviet empire then saved capitalism all over again by forcing it to reform itself out of fear. However, it was not the triumph of capitalism that brought down Soviet socialism in the end, but the global economic crisis which followed the end of the 'Golden Years' - a crisis the Soviet system was utterly unfit to withstand.

While never admitting to pessimism, Eric Hobsbawm considers that his Short Twentieth Century has ended with vast material advance but moral regression (unlike the 'Long Nineteenth Century' of his great trilogy on the Ages of Revolution, Capital and Empire, which produced both). Part of this regression is the decay of social solidarity, the widening gap between rich and poor. But another aspect of regression, in Hobsbawm's view, is nationalism. This is a phenomenon that he dislikes and - because of its tendency to rely upon fake history - despises.

In the opening of The Age of Empire, he told something of the story of his own family. The tale was meant to demonstrate the cosmopolitan reach of empires. But it also said something about his own attitude to the 'divisive nationalism' that followed imperial collapse. A young woman, born in Habsburg Vienna, travels to the Habsburg port of Trieste to visit her Uncle Albert who is running a business in Alexandria. A young man, whose father had migrated from the Tsarist empire to Britain, travels from London to take up a British imperial job in Egypt. There they meet, marry and in time become the parents of Eric.

It was not only to bourgeois Jewish families that the world before 1914 seemed a more open, enlightened and tolerant place than it became a few years later. Eric Hobsbawm began as a historian of the oppressed: those at the bottom of the heap. He is still that. But he has also become a historian of values, of the moral culture not only of the poor but of the rich and the rulers.

Eric Hobsbawm knew what Rosa Luxemburg meant, when she said that the alternative to socialism was not capitalism or imperialism but 'barbarism'. It is an old- fashioned word, and Hobsbawm would now put the alternatives in different terms. But when it comes down to good or evil, order or chaos, he is an old-fashioned moralist. This Central European intellectual, trained in the Marxist school, is the last British historian to use the word 'civilisation' with complete confidence.

Extracts from Eric Hobsbawm's 'Age of Extremes' begin in the Sunday Review next week.